应力历史对黏土–混凝土界面剪切特性的影响研究

 采用大型直剪仪，系统研究法向应力历史对黏土–混凝土界面剪切特性的影响。根据制定的加卸荷方案，对3个粗糙度等级(锯齿高为0，1，2 cm)的黏土–混凝土接触界面先加荷至初始法向应力，再卸荷至剪切法向应力进行剪切。从剪应力–剪切位移曲线、界面最大剪应力、剪胀性3个角度对试验结果进行对比分析。分析结果表明：黏土–混凝土界面剪应力–剪切位移曲线仍大体呈双曲线形式，并未出现应变软化现象。初始法向应力越大，相同剪切位移对应剪应力越大；初始法向应力越大对应的界面最大剪应力越大，根据Mohr-Coulomb准则通过线性拟合得出界面强度参数，并引入界面摩擦有效系数和黏聚有效系数。通过数据对比发现，界面黏聚有效系数随着初始法向应力的增大而增大，而摩擦有效系数则随初始法向应力的增大而减小。剪切过程中3个粗糙度等级的黏土–混凝土界面均发生不同程度的剪胀，界面越粗糙，剪胀量越大。同时，应力历史对界面剪胀性规律有明显的影响，未经历法向卸荷的界面剪切过程开始先剪缩然后再剪胀，而经历法向卸荷的界面剪切一开始便呈现剪胀，且初始法向应力越大，剪胀越明显。

RESEARCH ON EFFECT OF STRESS HISTORY ON SHEAR BEHAVIOR OF INTERFACE BETWEEN CLAY AND CONCRETE

A series of direct shear tests were carried out to study the effect of stress history on shear behavior of interface between clay and concrete.The clay-concrete interfaces of different roughnesses(sawtooth height of 0,1 and 2 cm,respectively) were loaded to an initial normal stress,then unloaded to a normal stress before shearing according to the schemes of loading and unloading.Results are presented for interface shear behavior in forms of shear stress-shear strain curves,vertical strain-shear strain curve...